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SAR Interferometric Data Inversion: A Study on Numerical Approaches

Giuseppe Puglisi(1) and Fabio Accetta(2)

(1) Ist. Naz. Geofisica e Vulcanologia, Piazza Roma, 2, 95123 Catania, Italy
(2) Università di Catania, Viale A. Doria, 6, 95125, Italy

Abstract

SAR interferometry is currently one of the most powerful techniques for observation of the Earth’s surface, in particular for topographical measurement of vast geographical areas and the measurement of changes of a surface over a pre-defined time interval (Differential Radar Interferometry). SAR interferometry allows integrating the techniques traditionally considered to measure ground deformations in volcanic areas such as EDM (Electronic Distance Measuring) or GPS (Global Positioning System) techniques. The inversion problem considered in this paper consists of identifying the parameters of a ground deformation source by observing the changes it causes in SAR interferometric data. Investigations into the structural analysis of the mathematical model, conceived by Okada (1985), show that the problem is an extremely nonlinear one. Hence the inversion solution cannot be obtained in closed form but it can be formulated as an optimization search problem. The search is tackled by using the Genetic Algorithms (GAs) approach since it guarantees against the problem of local minima. Synthetic data are first considered to study the accuracy of inverse solution. In the paper the problem of existence and uniqueness of the inverse solution is investigated. As a second step the inversion of actual data, which poses additional drawbacks, is considered.

 

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Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry